Exploration of the toxicity of ring-oxidized oxysterols and side chain-oxidized oxysterols in the context of inflammatory bowel diseases
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- Oxysterols are bioactive lipids involved in cholesterol homeostasis, bile acid synthesis and steroid hormone production. However, these molecules have also been associated with chronic diseases such as inflammatory bowel disease. Other works showed that oxysterols exert toxic effects on intestinal epithelial cells cultured as monolayers. Thus, oxysterols are suspected of disrupting the intestinal epithelial barrier and contributing to inflammation, although their specific effects on intestinal cells remain poorly studied. The aim of this master thesis is to evaluate and compare the toxicity of ring-oxidized oxysterols and side chain-oxidized oxysterols using 3D cell culture models, namely Caco-2 spheroids and mouse colon organoids. Spheroids and organoids were exposed to five sterol ring-oxidized and five side chain-oxidized oxysterols at 1 and 10 μM, and two incubation times, 24h and 48h, under normal and inflammatory conditions. Cell viability was assessed using the PrestoBlue® viability assay, LDH activity and size change. Inflammatory status was assessed by measuring the secretion of two pro-inflammatory cytokines, MCP-1 and TNF-α. The results showed that neither ring-oxidized oxysterols nor side chain-oxidized oxysterols significantly affected the viability of spheroids or organoids under normal or inflammatory conditions, even at concentrations above physiological levels. No significant increase in pro-inflammatory cytokines was observed. These results suggest that toxicity of oxysterols over epithelial cells might have been overestimated by previous works and more translational models like 3D cultures should be taken into account in toxicity studies.